Pressure range adjustment for respiratory therapy device

ABSTRACT

An automatic positive airway pressure (AutoPAP) therapy device can be configured such that the minimum and/or maximum pressures deliverable by the device can automatically change. The minimum and/or maximum pressures can change as a function of pressures delivered over the course of the current therapy session and/or over the course of prior therapy sessions. The minimum and/or maximum pressures can also change as a function of the presence, absence, type, severity, or length of sleep disordered breathing events (SDBE) detected by the device over the course of the current therapy session and/or over the course of prior therapy sessions.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

This application is a national phase of PCT/IB2015/051717, filed Mar.10, 2015, entitled “PRESSURE RANGE ADJUSTMENT FOR RESPIRATORY THERAPYDEVICE,” which claims priority to U.S. Prov. Pat. App. 61/950,746, filedMar. 10, 2014, entitled “PRESSURE RANGE ADJUSTMENT FOR RESPIRATORYTHERAPY DEVICE.” The application identified in this paragraph isincorporated by reference herein in its entirety. Any and allapplications for which a foreign or domestic priority claim isidentified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to respiratory therapy devices.More particularly, the present disclosure relates to control systems foruse with respiratory therapy devices.

BACKGROUND

Respiratory disorders deal with the inability of a sufferer to effect asufficient exchange of gases with the environment, leading to animbalance of gases in the sufferer. These disorders can arise as apathological consequence of an obstruction of the airway, insufficiencyof the lungs in generating negative pressure, an irregularity in thenervous function of the brain stem, or some other physiologicalcomplication. Treatment of such disorders is diverse and depends on theparticular respiratory disorder being targeted. In the first instance, aconstriction of the airway, otherwise known as an obstructive apnea or ahypopnea (collectively referred to as obstructive sleep apnea or OSA),can occur when the muscles that normally keep the airway open in apatient relax during slumber to the extent that the airway isconstrained or completely closed off, a phenomenon often manifestingitself in the form of snoring. When this occurs for a significant periodof time, the patient's brain typically recognizes the threat of hypoxiaand partially wakes the patient in order to open the airway so thatnormal breathing may resume. The patient may be unaware of theseoccurrences, which may occur as many as several hundred times persession of sleep. This partial awakening may significantly reduce thequality of the patient's sleep, over time potentially leading to avariety of symptoms, including chronic fatigue, elevated heart rate,elevated blood pressure, weight gain, headaches, irritability,depression and anxiety.

Obstructive sleep apnea is commonly treated with the application ofpositive airway pressure (PAP) therapy. PAP therapy involves deliveringa flow of gas to a patient at a therapeutic pressure above atmosphericpressure that may reduce the frequency and/or duration of apneas,hypopneas, and/or flow limitations. This therapy may be delivered byusing a positive airway pressure device (PAP device) to propel apressurized stream of air through a conduit to a patient through aninterface or mask located on the face of the patient. The stream of airmay be heated to near body temperature. The stream of air may behumidified. The humidification may be performed by forcing the stream ofair to travel through a respiratory humidifier containing water and aheater for heating the water. In such a system the heater encourages theevaporation of the water, which in turn partially or fully imbues thestream of air with moisture and/or heat. This moisture and/or heat mayhelp to ameliorate discomfort that may arise from the use ofunhumidified PAP therapy.

In respiratory therapy methods involving administration of pressurizedrespiratory gases to treat obstructive sleep apnea, it is known to useconstant positive airway pressure therapy, in which the pressuredelivered over the course of a therapy session remains constant. Anexample of such a therapy is shown in FIG. 2 as a pressure (P) versustime (T) graph. In some situations, bi-level PAP therapy (also known asBiPAP therapy) may be used to treat OSA. Bi-level PAP therapy may referto a PAP therapy in which a PAP device may be used to deliver a firstpressure at or around a detection of an inhalation of a patient (e.g.,an inhalation positive airway pressure or IPAP) and deliver a secondpressure at or around a detection of an exhalation of the patient (e.g.,an exhalation positive airway pressure or EPAP). To provide patientcomfort, the second pressure may be lower than the first pressure. Insome situations, the PAP device may reduce the pressure delivered from atherapeutic level to a sub-therapeutic level upon determination of awakeful state of the patient and increase the pressure delivered from asub-therapeutic level to a therapeutic level upon determination of anasleep state of the patient. In some situations, it is desirable toconfigure a PAP device in such a way that the pressure delivered isautomatically adjusted over the course of a therapy session to match theneeds of the patient. It is believed that utilizing high pressures onlywhen the patient requires high pressure therapy for a respiratorydisorder can improve the comfort of the therapy. Accordingly, anautomatically adjusting PAP device (AutoPAP device) capable of adjustingthe delivered pressure in such a way that the delivered pressure mayincrease or decrease upon the detection of the presence or absence ofsymptoms of a respiratory disorder may be provided. An example ofAutoPAP therapy is shown in FIG. 3 as a pressure versus time graph. Ascan be seen, the AutoPAP device may initially start the patient at apredetermined pressure (for example, P_(min) as shown in FIG. 1) andincrease the delivered pressure upon detection of a symptom of arespiratory disorder (for example, as shown at point a or point c inFIG. 3). The AutoPAP device may also decrease the delivered pressureupon detection of the absence of symptoms of a respiratory disorder fora period of time (for example, as shown at point d of FIG. 3). In suchan AutoPAP device, in at least one mode the range of pressures that thedevice may deliver may be bounded by a minimum pressure level definingthe lowest pressure deliverable by the device and a maximum pressurelevel defining the highest pressure deliverable by the device. In manycases, the minimum and/or maximum pressures are prescribed by a medicalprofessional, and the device is likewise configured by the professionalor a medical device dealer.

SUMMARY

In many cases, when a physician wishes to prescribe AutoPAP therapy fora patient with obstructive sleep apnea or another condition treatablewith PAP therapy, there is some difficulty in deciding on the correctpressure range for the AutoPAP device. If the pressure range selected istoo large, for example 4 cm H₂O to 18 cm H₂O, the minimum pressure ofthe range (e.g., 4 cm H₂O) may be too low to be therapeuticallyeffective, and the maximum pressure of the range (e.g., 18 cm H₂O) maybe greater than required for maximal therapeutic benefit and/or too highfor optimal patient comfort. If the pressure range selected is toosmall, for example 10 cm H₂O to 12 cm H₂O, the pressures administeredover the entire range may be too high for comfort or too low to beeffective, and/or the device may have a limited ability to compensatefor the onset of respiratory disorder symptoms. Faced with such aproblem, it is possible that the physician may initially prescribeAutoPAP therapy with a large pressure range, and have the patient use anAutoPAP device with this pressure range for a trial period, e.g., oneweek. During use, the AutoPAP device may record the pressures deliveredby the device during the trial period and the physician may, forexample, examine the recorded data during a subsequent visit with thepatient. The physician may then use his/her judgment to set anappropriate range of pressures for the patient based on the dataavailable.

In such a scenario, the physician spends additional time with thepatient and/or the patient's records, inconveniencing the physician andincreasing the burden on public and/or private healthcare systems.Accordingly, it is an object of the disclosure to provide an improvedPAP system that might solve one or more of the above problems, or atleast provide the public with a useful choice.

Thus, in accordance with at least one of the embodiments disclosedherein, a respiratory therapy system is disclosed. The respiratorytherapy system is configured to adjust the operational pressure range ofthe system based on sensed information about the treatment of thepatient as described herein. The respiratory therapy system may comprisea flow generator. The respiratory therapy system may comprise a sensor.The sensor may be adapted to measure at least one characteristic capableof being used to determine one or more traits of a sleep-disorderedbreathing event (SDBE) of the patient. The respiratory therapy systemmay comprise a controller. The controller may be configured to receivethe at least one characteristic measured by the sensor. The controllermay be configured to analyze the at least one characteristic. The atleast one characteristic may be analyzed to determine one or more traitsof an SDBE of the patient. The controller may control the flow generatorto maintain or adjust a pressure delivered by the flow generator betweena minimum and a maximum pressure, inclusive. The maintaining oradjusting may be at least in part based on the determined one or moretraits of an SDBE. The minimum and/or maximum pressures may be adjustedin response to one or more parameters recorded during the course of thecurrent therapy session and/or one or more previous or past therapysessions. The parameters may include at least one of the following: thepressure delivered and the one or more traits of the SDBE. In someconfigurations, the controller may control the flow generator tomaintain or adjust the pressure delivered by the flow generator betweena minimum and a maximum pressure, inclusive, on an event-by-event basis.In other words, the controller may react to individual SDBEs as they aredetected. In some configurations, the controller may make the decisionto change or not change the minimum and/or maximum pressures on asession-by-session basis, a time period-by-time period basis, anight-by-night basis, or on some other basis.

In some configurations, the characteristics capable of being used todetermine the one or more traits of an SDBE may include one or more ofthe following: gas pressure (e.g. delivered gas pressure), gas flow(e.g. delivered gas flow), sound, flow generator current (e.g. flowgenerator motor driving current), flow generator speed (e.g. flowgenerator motor speed), flow generator motor torque, motion (e.g.patient motion), tidal volume, heart rate, lung volume,electroencephalograph signal, EEG signal, EKG/ECG signal, breathcomposition, blood oxygen concentration, and blood CO2 concentration.The traits of an SDBE may include one or more of the following: thepresence of an SDBE, the absence of an SDBE, the type of SDBE, theseverity of SDBE, the length of the SDBE, and the latency of the SDBE.

The minimum pressure and/or maximum pressure may be adjusted in responseto the pressure delivered during the course of the present therapysession. The minimum pressure and/or maximum pressure may be adjusted inresponse to the pressure(s) delivered during the course of one or moreprevious therapy sessions. The minimum pressure and/or maximum pressuremay be adjusted in response to both the pressure delivered during thecourse of the present therapy session and the pressure(s) delivered overthe course of one or more previous therapy sessions. In someconfigurations, the delivered pressure at which the patient spent apercentage of time at or below over the course of one or more previoustherapy sessions may be recorded. The minimum and/or maximum pressuresmay be adjusted to a function of the recorded pressure.

In some configurations, if the patient spends a percentage of time atthe maximum pressure greater than or equal to a first or thresholdpercentage of time at the maximum pressure over the course of one ormore previous therapy sessions, the maximum pressure may be increased.The threshold percentage of time may be predetermined. In someconfigurations, if the patient spends a percentage of time at themaximum pressure less than or equal to a threshold percentage of time atthe maximum pressure over the course of one or more previous therapysessions, the maximum pressure may be decreased. The thresholdpercentage of time may be predetermined. In some configurations, if thepatient experiences a number of pressure increases at or near theminimum pressure that is greater than or equal to a predetermined numberover a predetermined period of time, the minimum pressure may beincreased.

Additionally, in accordance with at least one of the embodimentsdisclosed herein, a method for delivering a respiratory therapy isdisclosed. A pressurized gas may be delivered to a patient. At least onecharacteristic capable of being used to determine one or more traits ofa sleep-disordered breathing event (SDBE) may be measured. The at leastone characteristic may be analyzed to determine the one or more traitsof a sleep-disordered breathing event of the patient. The pressure ofthe pressurized gas delivered to the patient may be maintained oradjusted between a minimum pressure and a maximum pressure, inclusive.The pressure may be maintained or adjusted at least in part based on thedetermined one or more traits of an SDBE. The minimum and/or maximumpressures may be adjusted in response to one or more parameters recordedduring the course of the current therapy session and/or one or moreprevious or past therapy sessions. The parameters may include at leastone of the following: the pressure delivered and the one or more traitsof the SDBE. In some configurations, the decision to maintain or adjustthe pressure delivered between a minimum and a maximum pressure,inclusive, may be made on an event-by-event basis. In other words, adecision may be made to react to individual SDBEs as they are detected.In some configurations, a decision may be made to change or not changethe minimum and/or maximum pressures on an (SDBE) event-by-event basis,a session-by-session basis, a time period-by-time period basis, anight-by-night basis, or on some other basis.

In some configurations, the characteristics capable of being used todetermine the one or more traits of an SDBE may include one or more ofthe following: gas pressure (e.g. delivered gas pressure), gas flow(e.g. delivered gas flow), sound, flow generator current (e.g. flowgenerator motor driving current), flow generator speed (e.g. flowgenerator motor speed), flow generator motor torque, motion (e.g.patient motion), tidal volume, heart rate, lung volume, EEG signal,EKG/ECG signal, breath composition, blood oxygen concentration, andblood CO₂ concentration. The traits of an SDBE may include one or moreof the following: the presence of an SDBE, the absence of an SDBE, thetype of SDBE, the severity of SDBE, the length of the SDBE, and thelatency of the SDBE.

The minimum pressure and/or maximum pressure may be adjusted in responseto the pressure delivered during the course of the present therapysession. The minimum pressure and/or maximum pressure may be adjusted inresponse to the pressure(s) delivered during the course of one or moreprevious therapy sessions. The minimum pressure and/or maximum pressuremay be adjusted in response to both the pressure delivered during thecourse of the present therapy session and the pressure(s) delivered overthe course of one or more previous therapy sessions. In someconfigurations, the delivered pressure which the patient spent apercentage of time at or below over the course of one or more previoustherapy sessions may be recorded. The minimum and/or maximum pressuresmay be adjusted to a function of the recorded pressure.

In some configurations, if the patient spends a percentage of time atthe maximum pressure greater than or equal to a first or thresholdpercentage of time at the maximum pressure over the course of one ormore previous therapy sessions, the maximum pressure may be increased.The threshold percentage of time may be predetermined. In someconfigurations, if the patient spends a percentage of time at themaximum pressure less than or equal to a threshold percentage of time atthe maximum pressure over the course of one or more previous therapysessions, the maximum pressure may be decreased. The percentage of timemay be predetermined. In some configurations, if the patient experiencesa number of pressure increases at or near the minimum pressure that isgreater than or equal to a predetermined number over a predeterminedperiod of time, the minimum pressure may be increased.

In accordance with at least some configurations disclosed herein is amethod of delivering a respiratory therapy comprising: delivering apressurized gas to a patient with a flow generator, measuring with asensor at least one characteristic capable of being used to determineone or more traits of a sleep-disordered breathing event (SDBE) of thepatient, determining with a hardware controller the one or more traitsof the SDBE of the patient by analyzing the at least one characteristic,repeatedly adjusting a pressure window comprising a minimum pressurelimit and a maximum pressure limit in response to one or more parametersmeasured during the course of the current therapy session and/or one ormore previous therapy sessions, the one or more parameters including atleast pressure delivered or the determined one or more traits of theSDBE; and controlling the flow generator to deliver pressurized gases,the pressure of the pressurized gases being at least in part based onthe determined one or more traits of the SDBE, and the pressure of thepressurized gases being greater than or equal to the minimum pressurelimit and less than or equal to the maximum pressure limit, wherein theminimum pressure limit is less than the maximum pressure limit.

In some configurations the characteristics capable of being used todetermine the one or more traits of the SDBE include one or more of thefollowing: gas pressure, gas flow, sound, flow generator current, flowgenerator speed, flow generator motor torque, motion, tidal volume,heart rate, lung volume, EEG signal, breath composition, blood oxygenconcentration, and blood CO₂ concentration.

In some configurations the traits of the SDBE include one or more of thefollowing: presence of the SDBE, absence of the SDBE, type of SDBE,severity of the SDBE, length of the SDBE, and latency of the SDBE.

In some configurations a decision may be made to maintain or adjust thepressure delivered between the minimum pressure limit and the maximumpressure limit, inclusive, on an event-by-event basis.

In some configurations the therapy sessions comprise only the currenttherapy session.

In some configurations the therapy sessions comprise only one or moreprevious therapy sessions.

In some configurations the therapy sessions comprise both the currenttherapy session and one or more previous therapy sessions.

In some configurations the minimum pressure limit or the maximumpressure limit is adjusted in response to the pressure delivered duringthe course of the current therapy session and/or one or more previoustherapy sessions.

In some configurations the minimum pressure limit or the maximumpressure limit is adjusted in response to the pressure delivered duringone or more previous therapy sessions.

In some configurations the delivered pressure at which the patient spenta percentage of time at or below over the course of one or more previoustherapy sessions is recorded, and the minimum pressure limit or themaximum pressure limit is adjusted to a function of the recordedpressure.

In some configurations if the patient spends a time at the maximumpressure limit that is greater than or equal to a threshold percentageof time at the maximum pressure limit over the course of one or moreprevious therapy sessions, the maximum pressure limit is increased.

In some configurations if the patient spends a time at the maximumpressure limit that is less than or equal to a threshold percentage oftime at the maximum pressure limit over the course of one or moreprevious therapy sessions, the maximum pressure limit is decreased.

In some configurations if the patient experiences a number of deliveredpressure increases greater than a predetermined number over apredetermined period of time at or near the minimum pressure limit, theminimum pressure limit is increased.

In some configurations the respiratory therapy comprises automaticpositive airway pressure therapy.

In some configurations the minimum pressure limit or the maximumpressure limit is adjusted during a therapy session.

In some configurations both the minimum pressure limit and the maximumpressure limit are adjusted during the therapy session.

In accordance with at least some configurations disclosed herein is anon-transitory computer readable medium configured to store executableinstructions for a method of delivering a respiratory therapy, theexecutable instructions comprising: controlling a flow generator todeliver a pressurized gas to a patient, receiving from a sensormeasurements of at least one characteristic capable of being used todetermine one or more traits of a sleep-disordered breathing event(SDBE) of the patient, determining with a hardware controller the one ormore traits of the SDBE of the patient by analyzing the at least onecharacteristic, repeatedly adjusting a pressure window comprising aminimum pressure limit and a maximum pressure limit in response to oneor more parameters measured during the course of the current therapysession and/or one or more previous therapy sessions, the one or moreparameters including at least pressure delivered or the determined oneor more traits of the SDBE; and controlling the flow generator todeliver pressurized gases, the pressure of the pressurized gases beingat least in part based on the determined one or more traits of the SDBE,and the pressure of the pressurized gases being greater than or equal tothe minimum pressure limit and less than or equal to the maximumpressure limit, wherein the minimum pressure limit is less than themaximum pressure limit.

In some configurations the characteristics capable of being used todetermine the one or more traits of the SDBE include one or more of thefollowing: gas pressure, gas flow, sound, flow generator current, flowgenerator speed, flow generator motor torque, motion, tidal volume,heart rate, lung volume, EEG signal, breath composition, blood oxygenconcentration, and blood CO2 concentration.

In some configurations the traits of the SDBE include one or more of thefollowing: presence of the SDBE, absence of the SDBE, type of SDBE,severity of the SDBE, length of the SDBE, and latency of the SDBE.

In some configurations a decision may be made to maintain or adjust thepressure delivered between the minimum pressure limit and the maximumpressure limit, inclusive, on an event-by-event basis.

In some configurations the therapy sessions comprise only the currenttherapy session.

In some configurations the therapy sessions comprise only one or moreprevious therapy sessions.

In some configurations the therapy sessions comprise both the currenttherapy session and one or more previous therapy sessions.

In some configurations the minimum pressure limit or the maximumpressure limit is adjusted in response to the pressure delivered duringthe course of the current therapy session and/or one or more previoustherapy sessions.

In some configurations the minimum pressure limit or the maximumpressure limit is adjusted in response to the pressure delivered duringone or more previous therapy sessions.

In some configurations the delivered pressure at which the patient spenta percentage of time at or below over the course of one or more previoustherapy sessions is recorded, and the minimum pressure limit or themaximum pressure limit is adjusted to a function of the recordedpressure.

In some configurations if the patient spends a time at the maximumpressure limit that is greater than or equal to a threshold percentageof time at the maximum pressure limit over the course of one or moreprevious therapy sessions, the maximum pressure limit is increased.

In some configurations if the patient spends a time at the maximumpressure limit that is less than or equal to a threshold percentage oftime at the maximum pressure limit over the course of one or moreprevious therapy sessions, the maximum pressure limit is decreased.

In some configurations if the patient experiences a number of deliveredpressure increases greater than a predetermined number over apredetermined period of time at or near the minimum pressure limit, theminimum pressure limit is increased.

In some configurations the respiratory therapy comprises automaticpositive airway pressure therapy.

In some configurations the minimum pressure limit or the maximumpressure limit is adjusted during a therapy session.

In some configurations both the minimum pressure limit and the maximumpressure limit are adjusted during the therapy session.

In accordance with at least some configurations disclosed herein is arespiratory therapy system comprising: a flow generator adapted toprovide pressurized gases to a patient, a sensor adapted to measure atleast one characteristic capable of being used to determine one or moretraits of a sleep-disordered breathing event (SDBE) of the patient, anda hardware controller configured to: receive the at least onecharacteristic measured by the sensor, determine the one or more traitsof the SDBE of the patient by analyzing the at least one characteristic,adjust a pressure window for a first therapy session, the pressurewindow comprising a minimum pressure limit and a maximum pressure limit,wherein the hardware controller adjusts the pressure window in responseto one or more parameters measured during the course of one or moresecond therapy sessions, the one or more parameters including at leastthe determined one or more traits of the SDBE; and control the flowgenerator to deliver pressurized gases, the pressure of the pressurizedgases being at least in part based on the determined one or more traitsof the SDBE, and the pressure of the pressurized gases being greaterthan or equal to the minimum pressure limit and less than or equal tothe maximum pressure limit, wherein the minimum pressure limit is lessthan the maximum pressure limit.

In some configurations the characteristics capable of being used todetermine the one or more traits of the SDBE include one or more of thefollowing: gas pressure, gas flow, sound, flow generator current, flowgenerator speed, flow generator motor torque, motion, tidal volume,heart rate, lung volume, EEG signal, breath composition, blood oxygenconcentration, and blood CO2 concentration.

In some configurations the first therapy session is a current therapysession.

In some configurations the first therapy session is a future therapysession.

In some configurations the one or more second therapy sessions are pasttherapy sessions, wherein the one or more parameters measured during thecourse of one or more second therapy sessions comprises historical datameasured for the patient.

In accordance with at least some configurations disclosed herein is amethod of providing respiratory therapy, the method comprising:delivering pressurized gases to a patient using a flow generator;measuring with a sensor at least one characteristic capable of beingused to determine one or more traits of a sleep-disordered breathingevent (SDBE) of the patient; determining the one or more traits of theSDBE of the patient by analyzing the at least one characteristic;adjusting a pressure window for a first therapy session, the pressurewindow comprising a minimum pressure limit and a maximum pressure limit,wherein the hardware controller adjusts the pressure window in responseto one or more parameters measured during the course of one or moresecond therapy sessions, the one or more parameters including at leastthe determined one or more traits of the SDBE; and controlling the flowgenerator to deliver pressurized gases, the pressure of the pressurizedgases being at least in part based on the determined one or more traitsof the SDBE, and the pressure of the pressurized gases being greaterthan or equal to the minimum pressure limit and less than or equal tothe maximum pressure limit, wherein the minimum pressure limit is lessthan the maximum pressure limit.

In some configurations the characteristics capable of being used todetermine the one or more traits of the SDBE include one or more of thefollowing: gas pressure, gas flow, sound, flow generator current, flowgenerator speed, flow generator motor torque, motion, tidal volume,heart rate, lung volume, EEG signal, breath composition, blood oxygenconcentration, and blood CO2 concentration.

In some configurations the first therapy session is a current therapysession.

In some configurations the first therapy session is a future therapysession.

In some configurations the one or more second therapy sessions are pasttherapy sessions, wherein the one or more parameters measured during thecourse of one or more second therapy sessions comprises historical datameasured for the patient.

In accordance with at least some configurations disclosed herein is anon-transitory computer readable medium configured to store executableinstructions for a method of delivering a respiratory therapy, theexecutable instructions comprising: delivering pressurized gases to apatient using a flow generator; measuring with a sensor at least onecharacteristic capable of being used to determine one or more traits ofa sleep-disordered breathing event (SDBE) of the patient; determiningthe one or more traits of the SDBE of the patient by analyzing the atleast one characteristic, adjusting a pressure window for a firsttherapy session, the pressure window comprising a minimum pressure limitand a maximum pressure limit, wherein the hardware controller adjuststhe pressure window in response to one or more parameters measuredduring the course of one or more second therapy sessions, the one ormore parameters including at least the determined one or more traits ofthe SDBE; and controlling the flow generator to deliver pressurizedgases, the pressure of the pressurized gases being at least in partbased on the determined one or more traits of the SDBE, and the pressureof the pressurized gases being greater than or equal to the minimumpressure limit and less than or equal to the maximum pressure limit,wherein the minimum pressure limit is less than the maximum pressurelimit.

In some configurations the characteristics capable of being used todetermine the one or more traits of the SDBE include one or more of thefollowing: gas pressure, gas flow, sound, flow generator current, flowgenerator speed, flow generator motor torque, motion, tidal volume,heart rate, lung volume, EEG signal, breath composition, blood oxygenconcentration, and blood CO2 concentration.

In some configurations the first therapy session is a current therapysession.

In some configurations the first therapy session is a future therapysession.

In some configurations the one or more second therapy sessions are pasttherapy sessions, wherein the one or more parameters measured during thecourse of one or more second therapy sessions comprises historical datameasured for the patient.

In accordance with at least some configurations disclosed herein is arespiratory therapy system comprising: a flow generator adapted toprovide pressurized gases to a patient, a sensor adapted to measure atleast one characteristic capable of being used to determine one or moretraits of a sleep-disordered breathing event (SDBE) of the patient, anda hardware controller configured to: receive the at least onecharacteristic measured by the sensor, determine the one or more traitsof the SDBE of the patient by analyzing the at least one characteristic,repeatedly adjust a pressure window for a first therapy session, thepressure window comprising a minimum pressure limit and a maximumpressure limit, wherein the hardware controller adjusts the pressurewindow in response to one or more parameters measured during the courseof one or more second therapy sessions, the one or more parametersincluding pressure delivered to the patient; and control the flowgenerator to deliver pressurized gases, the pressure of the pressurizedgases being at least in part based on the determined one or more traitsof the SDBE, and the pressure of the pressurized gases being greaterthan or equal to the minimum pressure limit and less than or equal tothe maximum pressure limit, wherein the minimum pressure limit is lessthan the maximum pressure limit.

In some configurations the first therapy session is a current therapysession.

In some configurations the first therapy session is a future therapysession.

In some configurations the one or more second therapy sessions areprevious therapy sessions, wherein the one or more parameters measuredduring the course of one or more second therapy sessions compriseshistorical data measured for the patient.

In some configurations the minimum pressure limit or the maximumpressure limit is adjusted in response to the pressure delivered duringthe one or more previous therapy sessions.

In some configurations the delivered pressure at which the patient spenta percentage of time at or below over the course of one or more previoustherapy sessions is recorded, and the minimum pressure limit or themaximum pressure limit is adjusted to a function of the recordedpressure.

In some configurations if the patient spends a time at the maximumpressure limit that is greater than or equal to a threshold percentageof time at the maximum pressure limit over the course of one or moreprevious therapy sessions, the maximum pressure limit is increased.

In some configurations if the patient spends a time at the maximumpressure limit that is less than or equal to a threshold percentage oftime at the maximum pressure limit over the course of one or moreprevious therapy sessions, the maximum pressure limit is decreased.

In some configurations if the patient experiences a number of deliveredpressure increases greater than a predetermined number over apredetermined period of time at or near the minimum pressure limit, theminimum pressure limit is increased.

In accordance with at least some configurations disclosed herein is amethod for providing respiratory therapy to a patient, the methodcomprising: delivering pressurized gases to a patient using a flowgenerator; measuring with a sensor at least one characteristic capableof being used to determine one or more traits of a sleep-disorderedbreathing event (SDBE) of the patient; determining the one or moretraits of the SDBE of the patient by analyzing the at least onecharacteristic; repeatedly adjusting a pressure window for a firsttherapy session, the pressure window comprising a minimum pressure limitand a maximum pressure limit, wherein the hardware controller adjuststhe pressure window in response to one or more parameters measuredduring the course of one or more second therapy sessions, the one ormore parameters including pressure delivered to the patient; andcontrolling the flow generator to deliver pressurized gases, thepressure of the pressurized gases being at least in part based on thedetermined one or more traits of the SDBE, and the pressure of thepressurized gases being greater than or equal to the minimum pressurelimit and less than or equal to the maximum pressure limit, wherein theminimum pressure limit is less than the maximum pressure limit.

In some configurations the first therapy session is a current therapysession.

In some configurations the first therapy session is a future therapysession.

In some configurations the one or more second therapy sessions areprevious therapy sessions, wherein the one or more parameters measuredduring the course of one or more second therapy sessions compriseshistorical data measured for the patient.

In some configurations the one or more second therapy sessions areprevious therapy sessions, wherein the one or more parameters measuredduring the course of one or more second therapy sessions compriseshistorical data measured for the patient.

In some configurations the minimum pressure limit or the maximumpressure limit is adjusted in response to the pressure delivered duringthe one or more previous therapy sessions.

In some configurations the delivered pressure at which the patient spenta percentage of time at or below over the course of one or more previoustherapy sessions is recorded, and the minimum pressure limit or themaximum pressure limit is adjusted to a function of the recordedpressure.

In some configurations if the patient spends a time at the maximumpressure limit that is greater than or equal to a threshold percentageof time at the maximum pressure limit over the course of one or moreprevious therapy sessions, the maximum pressure limit is increased.

In some configurations if the patient spends a time at the maximumpressure limit that is less than or equal to a threshold percentage oftime at the maximum pressure limit over the course of one or moreprevious therapy sessions, the maximum pressure limit is decreased.

In some configurations if the patient experiences a number of deliveredpressure increases greater than a predetermined number over apredetermined period of time at or near the minimum pressure limit, theminimum pressure limit is increased.

In accordance with at least some configurations disclosed herein is anon-transitory computer readable medium configured to store executableinstructions for a method of delivering a respiratory therapy, theexecutable instructions comprising: delivering pressurized gases to apatient using a flow generator; measuring with a sensor at least onecharacteristic capable of being used to determine one or more traits ofa sleep-disordered breathing event (SDBE) of the patient; determiningthe one or more traits of the SDBE of the patient by analyzing the atleast one characteristic; repeatedly adjusting a pressure window for afirst therapy session, the pressure window comprising a minimum pressurelimit and a maximum pressure limit, wherein the hardware controlleradjusts the pressure window in response to one or more parametersmeasured during the course of one or more second therapy sessions, theone or more parameters including pressure delivered to the patient; andcontrolling the flow generator to deliver pressurized gases, thepressure of the pressurized gases being at least in part based on thedetermined one or more traits of the SDBE, and the pressure of thepressurized gases being greater than or equal to the minimum pressurelimit and less than or equal to the maximum pressure limit, wherein theminimum pressure limit is less than the maximum pressure limit.

In some configurations the first therapy session is a current therapysession.

In some configurations the first therapy session is a future therapysession.

In some configurations the one or more second therapy sessions areprevious therapy sessions, wherein the one or more parameters measuredduring the course of one or more second therapy sessions compriseshistorical data measured for the patient.

In some configurations the one or more second therapy sessions areprevious therapy sessions, wherein the one or more parameters measuredduring the course of one or more second therapy sessions compriseshistorical data measured for the patient.

In some configurations the minimum pressure limit or the maximumpressure limit is adjusted in response to the pressure delivered duringthe one or more previous therapy sessions.

In some configurations the delivered pressure at which the patient spenta percentage of time at or below over the course of one or more previoustherapy sessions is recorded, and the minimum pressure limit or themaximum pressure limit is adjusted to a function of the recordedpressure.

In some configurations the patient spends a time at the maximum pressurelimit that is greater than or equal to a threshold percentage of time atthe maximum pressure limit over the course of one or more previoustherapy sessions, the maximum pressure limit is increased.

In some configurations if the patient spends a time at the maximumpressure limit that is less than or equal to a threshold percentage oftime at the maximum pressure limit over the course of one or moreprevious therapy sessions, the maximum pressure limit is decreased.

In some configurations if the patient experiences a number of deliveredpressure increases greater than a predetermined number over apredetermined period of time at or near the minimum pressure limit, theminimum pressure limit is increased.

In accordance with at least some configurations disclosed herein is arespiratory therapy system comprising: a flow generator adapted toprovide pressurized gases to a patient, a sensor adapted to measure atleast one characteristic capable of being used to determine one or moretraits of a sleep-disordered breathing event (SDBE) of the patient, anda hardware controller configured to: in a first therapy mode, controlthe flow generator to deliver pressurized gases at a first pressurelevel for a first time period and to deliver pressurized gases at asecond pressure level for a second time period; determine for each ofthe first time period and the second time period a sleep index based onone or more traits of the SDBE of the patient by analyzing the at leastone characteristic; and determine a pressure window of a second therapymode, the pressure window comprising a minimum pressure limit and amaximum pressure limit, wherein the hardware controller determines thepressure window by using a continuous function that associates a sleepindex with a pressure level and by using the continuous function todetermine a tailored pressure level that achieves a targeted sleepindex; and defining the minimum pressure limit and the maximum pressurelimit of the pressure window based on the tailored pressure level;wherein the minimum pressure limit is less than the maximum pressurelimit.

In some configurations the targeted sleep index is an optimizationutilizing the continuous function.

In some configurations the targeted sleep index is a minimum of thecontinuous function.

In some configurations the targeted sleep index is a maximum of thecontinuous function.

In accordance with at least some configurations disclosed herein is amethod of providing respiratory therapy, the method comprising:delivering pressurized gases to a patient using a flow generator;measuring with a sensor at least one characteristic capable of beingused to determine one or more traits of a sleep-disordered breathingevent (SDBE) of the patient; in a first therapy mode, controlling theflow generator to deliver pressurized gases at a first pressure levelfor a first time period and to deliver pressurized gases at a secondpressure level for a second time period; determining for each of thefirst time period and the second time period a sleep index based on oneor more traits of the SDBE of the patient by analyzing the at least onecharacteristic; determining a pressure window of a second therapy mode,the pressure window comprising a minimum pressure limit and a maximumpressure limit, wherein the hardware controller determines the pressurewindow by using a continuous function that associates a sleep index witha pressure level and by using the continuous function to determine atailored pressure level that achieves a targeted sleep index; anddefining the minimum pressure limit and the maximum pressure limit ofthe pressure window based on the tailored pressure level; wherein theminimum pressure limit is less than the maximum pressure limit.

In some configurations the targeted sleep index is an optimizationutilizing the continuous function.

In some configurations the targeted sleep index is a minimum of thecontinuous function.

In some configurations the targeted sleep index is a maximum of thecontinuous function.

In accordance with at least some configurations disclosed herein is anon-transitory computer readable medium configured to store executableinstructions for a method of delivering a respiratory therapy, theexecutable instructions comprising: delivering pressurized gases to apatient using a flow generator; measuring with a sensor at least onecharacteristic capable of being used to determine one or more traits ofa sleep-disordered breathing event (SDBE) of the patient; in a firsttherapy mode, controlling the flow generator to deliver pressurizedgases at a first pressure level for a first time period and to deliverpressurized gases at a second pressure level for a second time period;determining for each of the first time period and the second time perioda sleep index based on one or more traits of the SDBE of the patient byanalyzing the at least one characteristic; determining a pressure windowof a second therapy mode, the pressure window comprising a minimumpressure limit and a maximum pressure limit, wherein the hardwarecontroller determines the pressure window by using a continuous functionthat associates a sleep index with a pressure level and by using thecontinuous function to determine a tailored pressure level that achievesa targeted sleep index; and defining the minimum pressure limit and themaximum pressure limit of the pressure window based on the tailoredpressure level; wherein the minimum pressure limit is less than themaximum pressure limit.

In some configurations the targeted sleep index is an optimizationutilizing the continuous function.

In some configurations the targeted sleep index is a minimum of thecontinuous function.

In some configurations the targeted sleep index is a maximum of thecontinuous function.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments and modifications thereof will become apparent tothose skilled in the art from the detailed description herein havingreference to the figures that follow, of which:

FIG. 1 shows a schematic diagram of a respiratory therapy system.

FIG. 2 shows a pressure versus time graph demonstrating an example ofconstant positive airway pressure therapy.

FIG. 3 shows a pressure versus time graph demonstrating an example ofautomatic positive airway pressure (AutoPAP or APAP) therapy.

FIG. 4 shows a pair of pressure versus time graphs demonstrating anexample of AutoPAP therapy wherein the minimum and maximum pressureschange as a function of the pressure administered over the course of atherapy session.

FIG. 5 shows a pair of pressure versus time graphs demonstrating anexample of AutoPAP therapy wherein the maximum pressure increasesrelative to the time spent delivering the maximum pressure.

FIG. 6 shows a pair of pressure versus time graphs demonstrating anexample of AutoPAP therapy wherein the maximum pressure decreasesrelative to the time spent delivering the maximum pressure.

FIG. 7 shows a pair of pressure versus time graphs demonstrating anexample of AutoPAP therapy wherein the minimum pressure increases as afunction of the frequency of events occurring at the minimum pressure.

FIGS. 8A-8D show a set of pressure versus time graphs demonstratingseveral therapy sessions of constant PAP therapy, wherein the pressureused for each of the several therapy sessions is different.

FIG. 9 shows a method for selecting minimum and/or maximum pressures forAutoPAP therapy based on a set of pressures used in several sessions ofconstant PAP therapy.

FIG. 10 shows a relationship between constant PAP pressures and AHIvalues.

FIG. 11 shows a flow chart of an example method for adjusting a pressurerange for respiratory therapy.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Aspects of at least one of the configurations disclosed herein includesthe realization that an AutoPAP system can be configured to not onlyautomatically change the instant pressure delivered to the patientduring a therapy session, but additionally to automatically change, atleast in one mode of operation, the minimum and/or maximum pressuresdeliverable by the AutoPAP system.

With reference to FIG. 1, a configuration for a respiratory therapysystem 100 is shown. In the illustrated configuration, the respiratorysystem 100 may comprise a flow generator 101. The flow generator 101 maycomprise a gas inlet 102 and a gas outlet 104. The flow generator maycomprise a blower 106. The blower 106 may comprise a motor. The motormay comprise a stator and a rotor. The rotor may comprise a shaft. Animpeller may be linked to the shaft. In use, the impeller may rotateconcurrently with the shaft to draw in gas from the gas inlet 102. Theflow generator 101 may comprise a user interface 108 which may compriseone or more buttons, knobs, dials, switches, levers, touch screens,and/or displays so that a user might view data related to the operationof the flow generator 101 or to other components of the respiratorytherapy system 100 or input operation parameters into the flow generator101 to control its operation or the operation of other aspects of therespiratory therapy system 100. The flow generator 101 may pass gasthrough the gas outlet 104 to a first conduit 110. The first conduit 110may pass the gas to a humidifier 112 that may entrain moisture in thegas to provide a humidified gas stream. The humidifier 112 may comprisea humidifier inlet 116 and a humidifier outlet 118. The humidifier 112may comprise a reservoir 114 that may be filled with water or some otherhumidifying agent. The humidifier 112 may comprise a heating element113. The heating element 113 may be used to heat the humidifying agentin the reservoir 114 to encourage agent vaporization and/or entrainmentin the gas flow and/or increase the temperature of gases passing throughthe humidifier 112. The humidifier 112 may have a user interface 120which may comprise one or more buttons, knobs, dials, switches, levers,touch screens, and/or displays so that a user might view data related tothe operation of the humidifier 112 or to other components of therespiratory therapy system 100 or input operation parameters into thehumidifier 112 to control the operation of the heating element 113,operation of other aspects of the humidifier 112, and/or other aspectsof the respiratory therapy system 100. Gas may then pass from thehumidifier outlet 118 to a second conduit 122. The second conduit 122may comprise a heater. The heater may be used to add heat to gasespassing through the second conduit 122 in order to prevent thecondensation of moisture entrained in the gas stream along the walls ofthe second conduit 122. The heater may comprise one or more resistivewires located in, on, around or near the walls of second conduit 122.Gas passing through the second conduit 122 may then enter a patientinterface 124 that may pneumatically link the respiratory therapy system100 to the patient's airway. The patient interface 124 may comprise anasal mask, an oral mask, an oro-nasal mask, a full face mask, a nasalpillows mask, a nasal cannula, an endotracheal tube, a combination ofthe above or some other gas conveying system. The flow generator 101,humidifier 112, and/or other parts of the respiratory therapy system 100may comprise a controller (not shown). The controller may be amicroprocessor. The controller may help to control the operation of theflow generator 101, humidifier 112, and/or other aspects or operationparameters of the respiratory therapy system 100.

In the illustrated configuration, and as implied above, the respiratorytherapy system 100 may operate as follows: gas may be drawn into theflow generator 101 through the gas inlet 102 due to the rotation of animpeller of the motor of the blower 106. Gas may then be propelled outof the gas outlet 104 and along the first conduit 110. The gas flow mayenter the humidifier 112 through the humidifier inlet 116. Once in thehumidifier 112, the gas may pick up moisture while passing over thehumidification agent in the reservoir 114. The humidification agent inthe reservoir 114 may be heated by the heating element 113, which mayaid in the humidification and/or heating of the gas passing through thehumidifier 112. The gas may then leave the humidifier 112 through thehumidifier outlet 118 and enter the second conduit 122. Gas may then bepassed from the second conduit 122 to the patient interface 124, whereit may be taken into the patient's airways to aid in the treatment ofrespiratory disorders.

It should be understood that the illustrated configuration should not betaken to be limiting, and that many other configurations for therespiratory therapy system 100 are possible. In some configurations, theflow generator 101 may, for example, comprise a source or container ofcompressed air. The container may comprise a valve that may be adjustedto control the flow of gas leaving the container. In someconfigurations, the flow generator 101 may use such a source ofcompressed air or another gas source in lieu of a blower 106. In someconfigurations the blower 106 may be used in conjunction with anothergas source. In some configurations the flow generator 101 may draw inatmospheric gases through the gas inlet 102. In some configurations theflow generator 101 may be adapted to both draw in atmospheric gasesthrough the gas inlet 102 and accept other gases (e.g. oxygen, nitricoxide, carbon dioxide, etc.) through the same inlet 102 or a differentinlet. In some configurations the humidifier 112 can be integrated withthe flow generator 101. In some configurations the humidifier 112 andthe flow generator 101 may share a housing. In some such configurationsonly a single conduit extending between the flow generator 101 and thepatient interface 124 need be used to convey gases to a patient. In someconfigurations, the humidifier 112 may not be present. In some suchconfigurations, the first conduit 110 and the second conduit 122 may bereplaced with a single conduit extending from the flow generator 101 tothe patient interface 124. In some configurations, the flow generator101 and the humidifier 112 may have a single user interface located oneither the flow generator 101 or the humidifier 112. In someconfigurations, the operation of the flow generator 101, of thehumidifier 112, or of other aspects of the respiratory therapy system100 may be controlled a single controller. In some configurations, theoperation of the flow generator 101, of the humidifier 112, or of otheraspects of the respiratory therapy system 100 may be controlledwirelessly using a user interface located on a remote computing device.In some configurations, the respiratory therapy system 100 may compriseone or more sensors for detecting various characteristics of the gas,including pressure and/or flow rate.

The respiratory therapy system 100 may comprise one or more sensorscapable of detecting one or more characteristics of the patient,characteristics of the respiratory activity of the patient,characteristics of the respiratory therapy system 100, data related tothe operation of the respiratory therapy system 100, and/orcharacteristics of gases moving through the respiratory therapy system100. The one or more sensors may include one or more of the following: apressure sensor, a flow sensor, a sound sensor, a motor currenttransducer, a motor speed transducer, a motor torque transducer, a heartrate sensor, a plethysmograph, an electroencephalograph (EEG), anelectrocardiograph (ECG), a motion sensor, a breath composition sensor,a pulse oximeter, a blood oxygen concentration sensor, and a blood CO2concentration sensor. The characteristics obtainable from the one ormore sensors may include one or more of the following: gas pressure, gasflow, sound, flow generator motor current, flow generator motor speed,flow generator motor torque, heart rate, tidal volume, lung volume, EEGsignal, ECG signal, movement, breath composition, blood oxygenconcentration, and blood CO2 concentration. The one or more sensors maybe physically part of the respiratory therapy system 100 or wired to apart of the respiratory therapy system 100. In some configurations, theone or more sensors may be remote from the respiratory therapy system100. The one or more sensors may be capable of wireless communicationwith the respiratory therapy system 100. Measurements obtained by theone or more sensors of the respiratory therapy system 100 may be used todetermine, for example, a trait of a sleep-disordered breathing event(SDBE) of a patient using the respiratory therapy system 100. Acontroller of the respiratory therapy system 100, which may be, forexample, a microprocessor, may use the characteristics obtained by theone or more sensors to determine a trait of the SDBE. The controller ofthe respiratory therapy system 100 may be physically part of therespiratory therapy system 100 or wired to a part of the respiratorytherapy system 100. In some configurations, the controller may be remotefrom the respiratory therapy system 100, e.g., on a remote server or amobile device (e.g., a tablet or cellular phone). The controller may becapable of wireless communication with the respiratory therapy system100. Determined traits of the SDBE may include the presence, absence,type, severity, and/or length of the SDBE. The type of an SDBE mayinclude one or more of the following: an apnea, a hypopnea, and a flowlimitation. The severity of an SDBE may be a numerical indicator or maybe a qualitative designation that may be applied to a particular SDBE,e.g. ‘mild,’ ‘moderate,’ or ‘severe.’ In some cases, an SDBE may bepredicted by the characteristics of the respiratory flow preceding anSDBE. For example, in some cases, an apnea event may be predicted byanalysis of the flow waveform of breaths preceding the apnea. Oneadditional trait of an SDBE may be the latency of the SDBE, which may bedefined as a function of one or more qualities of the respiratoryactivity of the patient preceding the SDBE. The qualities may be one ormore of a flow waveform, a pressure waveform, motion of the patient, orsome other indicator of respiratory activity preceding an SDBE.

Attention is now given to use of a respiratory therapy system 100configured for use as an AutoPAP device. In such a device, therespiratory therapy system 100 may comprise a controller that, in atleast one mode of operation, may define a range of pressures. The rangeof pressures may be bounded by a minimum pressure level defining thelowest pressure deliverable by respiratory therapy system 100 and/or bya maximum pressure level defining the highest pressure deliverable bythe respiratory therapy system 100. The minimum and/or maximum pressuresmay be the pressures delivered to the patient or pressures taken at anypoint of the respiratory therapy system 100. The minimum and maximumpressures may be different pressures. The flow generator 101 may becontrolled such that the respiratory therapy system 100 may deliver apressure to the patient that is no less than the minimum pressure leveland no greater than the maximum pressure level. The AutoPAP device maybe configured to detect one or more traits of an SDBE experienced by apatient during a therapy session and respond by maintaining or adjustingthe pressure delivered by the respiratory therapy system 100 based onthe traits to accommodate the therapy and/or comfort needs of thepatient. For example, upon detecting that the patient is experiencing anepisode of obstructive sleep apnea, the respiratory therapy system 100may increase the pressure delivered to compensate for the apnea episode.Similarly, upon detecting the absence of an SDBE for a period of time,the respiratory therapy system 100 may decrease the pressure deliveredto improve the comfort of the therapy for the patient. In someconfigurations, BiPAP therapy may be used in conjunction with AutoPAPtherapy. In some such configurations, the therapeutic pressure (e.g. theinstant pressure delivered during AutoPAP therapy) may be the pressureused during patient inhalation, and the pressure may be lowered uponpatient exhalation. In some configurations, the therapeutic pressuredelivered may be the pressure used during patient exhalation, and thepressure may be increased upon patient inhalation. In someconfigurations, the EPAP may not be less than the minimum pressure. Insome configurations, the IPAP may not be greater than the maximumpressure.

Several methods of automatically adjusting the minimum and maximumpressures of an AutoPAP device are described herein. With reference toFIG. 4, a pair of graphs showing pressure versus time depict a methodfor adjusting the minimum and maximum pressures of an AutoPAP device. Onthe left graph, a therapy session (hereinafter referred to as the‘current’ therapy session) in which AutoPAP therapy is used is shown. Ascan be observed, the session may begin with the device delivering theminimum pressure (although in some configurations, other startingpressures may be used), and the pressure delivered may graduallyincrease and decrease as the patient experiences apneas, hypopneas, orother SDBEs, or the absence of SDBEs, or other conditions warranting apressure adjustment. The device may record data indicative of thepressures delivered over the course of the current therapy session. Insome configurations, during or after the current therapy session, thedevice may analyze the data recorded over the current therapy sessionand/or the data recorded over one or more past therapy sessions. Thedata recorded may be used to determine a target pressure P_(t) which thepatient spent at least an amount of time T at or under. In this example,the amount of time T is predetermined to be at least 90% of the totaltime of the current therapy session. However, the amount of time couldbe at least a predetermined number of hours (e.g., 3 hours, 10 hours, 20hours, 30 hours, etc.), another percentage of the therapy session (e.g.,at least 95% of the total time, at least 85% of the total time, at least80% of the total time, at least 75% of the total time, etc.), apercentage of one or more past therapy sessions (e.g., at least 95% ofpast therapy sessions, at least 85% of past therapy sessions, at least80% of past therapy sessions, at least 75% of past therapy sessions,etc.), a variable amount of time determined as a function of othervariables of the current or past sessions of use, or a combination ofthe above. In some configurations, the device may determine a targetpressure P_(t) at or under which the patient spent at least an amount oftime T, where the time T may be an average of times spent over thecourse of multiple therapy sessions or periods of time. For example, theamount of time T may be predetermined to be an average of at least 90%of the total time of the current therapy session and the last twoprevious sessions. In such an example, if all of the therapy sessionsare 8 hours in length, and the patient spends 85% of the first previoussession at or under the target pressure P_(t), 90% of the secondprevious session at or under the target pressure P_(t), and 95% of thecurrent session at or under the target pressure P_(t), the averageamount of time T which the patient spends at or under the targetpressure P_(t) may be determined to be 90%. This target pressure P_(t)may be considered a pressure which is therapeutically effective for thepatient. The minimum and maximum pressures may be adjusted to a functionof the target pressure P_(t). In some configurations, the minimum and/ormaximum pressures may be changed to the target pressure P_(t) minusand/or plus a pressure offset P_(o), respectively. The pressure offsetP_(o) may be predetermined or may be a function of the target pressureP_(t) or of some other variable. In some configurations, multiplepressure offsets may be used—for example, a minimum pressure offsetP_(o) _(_) _(min) may be used to calculate the minimum pressure from thetarget pressure P_(t) and a maximum pressure offset P_(o) _(_) _(max)may be used to calculate the maximum pressure from the target pressureP_(t). In the illustrated example, the target pressure P_(t) at whichthe patient spent 90% of the therapy session at or under was calculatedto be 10 cm H₂O. The pressure offset P_(o) was predetermined to be 2 cmH₂O. Correspondingly, as can be seen on the right graph, the minimumpressure has been changed to 8 cm H₂O (10 cm H₂O−2 cm H₂O) and themaximum pressure has been changed to 12 cm H₂O (10 cm H₂O+2 cm H₂O).This new pressure range (8 to 12 cm H₂O) may be used for subsequenttherapy sessions, and may be more therapeutically effective for thepatient than the original pressure range (4 to 18 cm H₂O) while stillallowing some improved flexibility and comfort over traditional constantPAP therapy.

In some configurations, constant PAP therapy may be used for severalperiods of time, and a target pressure P_(t) may be determined afteranalyzing data recorded during these periods of time. A period of timemay be a number of seconds, a number of minutes, a number of hours, anumber of days, a therapy session, a number of therapy sessions, apercentage of a therapy session, or some other quantity of time. In somesuch configurations, a PAP device may be used (which may be the AutoPAPdevice or some other PAP device) to administer constant PAP therapy overthe course of several periods of time. The individual time periods maybe successive or may be staggered (e.g., non-successive). The pressuredelivered during the individual time periods may be different such thatdifferent measurements relating to the traits of SDBEs or quality ofsleep over the course of each individual time period may be obtained. Insome configurations, a sleep index S_(i) may be determined indicatingsome aspect of the SDBE traits determined over the course of a timeperiod. The sleep index S_(i) may, for example, be an apnea-hypopneaindex (AHI), total apnea event count, total hypopnea event count, totalflow limitation event count, a combination of some or all of the above,or some other value. In some configurations, a sleep quality indexSQ_(i) may be determined indicating a value derived from a function ofone or more sleep indices S_(i). The determined sleep quality indexSQ_(i) may comprise a numeral indicator quantifying the perceived sleepquality for a given time period. In some such configurations, highersleep quality indices SQ_(i) indicate high sleep qualities. The sleepindex/indices Si and/or the sleep quality index/indices SQ_(i) obtainedfor each individual time period may be compared with each other at theend of the several periods of time. For example, the lowest sleep indexSi and/or highest sleep quality index SQ_(i) among the set of sleepindices or sleep quality indices SQ_(i) found for the several periods oftime may be determined. The target pressure P_(t), minimum pressureand/or maximum pressure may then be set to the CPAP pressure used duringthe period of time at which the lowest sleep index S_(i) and/or highestsleep quality index SQ_(i) was found, or a function of the CPAP pressureused during this period of time. In some configurations minimum and/ormaximum pressures may be derived from the target pressure P_(t), andAutoPAP therapy can be utilized based on the therapy range established.This may be actuated by using one or more offset pressures P_(o) asdescribed herein.

To demonstrate the above, attention is now given to FIGS. 8A-8D. In theillustrated configuration, the several time periods may be severaltherapy sessions. In FIG. 8A, constant PAP therapy at a pressure of 8 cmH₂O is used for a first therapy session. In FIG. 8B, constant PAPtherapy at a pressure of 10 cm H₂O is used for a second therapy session.In FIG. 8C, constant PAP therapy at a pressure of 12 cm H₂O is used fora third therapy session. In FIG. 8D, constant PAP therapy at a pressureof 14 cm H₂O is used for a fourth therapy session. An apnea-hypopneaindex (AHI) may be calculated for each individual therapy session and atarget pressure P_(o) may be set to the CPAP pressure used during thetherapy session on which the lowest AHI was recorded. In the illustratedconfiguration, an AHI of 30/hour was obtained for the first therapysession, an AHI of 20/hour was obtained for the second therapy session,an AHI of 7/hour was obtained for the third therapy session, and an AHIof 5/hour was obtained for the fourth therapy session. The AHI of 5/hourfor the fourth therapy session was the lowest AHI recorded over thecourse of the several therapy sessions, and so the target pressure P_(t)may be set to 14 cm H₂O. A pressure offset P_(o) may be used todetermine a minimum pressure and/or a maximum pressure. For example, ifthe pressure offset P_(o) is predetermined to be 2 cm H2O, then theminimum pressure may be set to (14 cm H₂O−2 cm H₂O) or 12 cm H₂O and themaximum pressure may be set to (14 cm H₂O+2 cm H₂O) or 16 cm H₂O. Forthe fifth and/or other future therapy sessions, instead of constant PAPtherapy, AutoPAP therapy may be used with a minimum pressure of 12 cmH₂O and a maximum pressure of 16 cm H₂O. The minimum and maximum rangesthereon may be changed through the use of other methods identical orsimilar to those disclosed herein. In other configurations apredetermined AHI value may be established and the target pressure P_(o)may be set to the lowest CPAP pressure for which the calculated AHI wasless than or equal to the predetermined AHI value or a function of thelowest CPAP pressure. In other configurations the minimum and/or maximumpressures may be set to some other function of the target pressureP_(o).

In some configurations, the minimum and/or maximum pressures may beselected based on a range of sleep indices S_(i) and/or sleep qualityindices SQ_(i). With continued reference to FIGS. 8A-8D, constant PAPtherapy may be used for several therapy sessions, wherein a differentconstant PAP pressure may be used for each individual therapy session.Similarly, sleep indices S_(i) and/or sleep quality indices SQ_(i) maybe calculated for each individual therapy session. FIG. 9 demonstrates apressure versus sleep index S_(i) function, although it should beunderstood that a similar graph may be used to illustrate a pressureversus sleep quality index SQ_(i) function. As shown in FIG. 9, arelationship between the sleep indices S_(i) and/or sleep qualityindices SQ_(i) and the CPAP pressures used may be found. The sleepindices S_(i) and/or sleep quality indices SQ_(i) may be plotted againstthe CPAP pressures used. A polynomial function may be found describingthe relationship between the sleep indices S_(i) and/or sleep qualityindices SQ_(i) and the CPAP pressures used. In some configurations, arange of sleep indices Si bounded by a minimum sleep index value S_(i)_(_) _(min) and a maximum sleep index value S_(i) _(_) _(max) may bedefined. The range may be predetermined. The minimum sleep index valueS_(i) _(_) _(min) may designate a first predetermined sleep index valuewhere gas therapies resulting in sleep index values under the firstpredetermined sleep index value are considered sub-optimal. The maximumsleep index value S_(i) _(_) _(max) may designate a second predeterminedsleep index value where gas therapies resulting in sleep index valuesover the second predetermined sleep index value are consideredsub-optimal. Minimum and/or maximum pressures may be determined fromanalysis of the polynomial function by determining a minimum pressure atwhich a minimum sleep index S_(i) _(_) _(min) may be observed and/or amaximum pressure at which a maximum sleep index S_(i) _(_) _(max) may beobserved. As an example, as seen in FIGS. 8A-8D, four sessions oftherapy may be recorded in which different constant PAP pressures (inthis case, 8 cm H₂O for the first session, 10 cm H₂O for the secondsession, 12 cm H₂O for the third session, and 14 cm H₂O for the fourthsession) are used and different AHI values (the sleep indices S_(i) inthis case) may be obtained for each session (in this case, AHI values of30/hour for the first session, 20/hour for the second session, 7/hourfor the third session, and 5/hour for the fourth session). As seen inFIG. 10, the relationship between the constant PAP pressures used andthe AHI values obtained may be plotted. A polynomial function showingthe AHI as a function of the CPAP pressure used may be found, and thepressures corresponding to the minimum AHI value and/or the maximum AHIvalue may be found. In this example, and as demonstrated by FIGS. 8A-8Dand FIG. 10, the minimum AHI value was predetermined to be 5/hour andthe maximum AHI value was predetermined to be 7/hour. The pressurescorresponding to the minimum and maximum AHI values were found to be 14cm H₂O and 12 cm H₂O, respectively. In this example, AutoPAP therapy maythen be used, where 12 cm H₂O may be assigned as the minimum pressureand 14 cm H₂O may be assigned as the maximum pressure.

In some configurations, if the maximum pressure deliverable isdetermined to be too low, the AutoPAP device may automatically increasethe maximum pressure. With reference to FIG. 5, a pair of pressureversus time graphs depicting a method for adjusting the maximum pressurefor an AutoPAP device is shown. On the left graph, a therapy session inwhich AutoPAP is used is shown. As can be observed, the session maybegin at the minimum pressure (but may begin at some other pressure) andmay increase to a higher pressure upon detecting apneas, hypopneas, orother SDBEs. The pressure may increase to the maximum pressure. After orover the course of a monitoring period (which may be a number of hours,a portion of a therapy session, an entire therapy session, multipletherapy sessions, or some other period of time), the amount of timeT_(max) _(_) _(total) over which the device delivers the maximumdeliverable pressure may be calculated or monitored. If the T_(max) _(_)_(total) is determined to be greater than or equal to a thresholdpercentage T % of the monitoring period, the device may increase themaximum deliverable pressure. The maximum pressure may be adjusted, forexample, immediately after the determination, a period of time after thedetermination, or during a subsequent therapy session. In theillustrated example, the T_(max) _(_) _(total) (here, T₁+T₂+T₃+T₄) wasfound to be 50% of the monitoring period, the T % was predetermined tobe 10% of the monitoring period, and the monitoring period waspredetermined to be an entire therapy session. The T_(max) _(_) _(total)was determined to be greater than the T %, and so the maximum pressure18 cm H₂O was increased to 19 cm H₂O. In some configurations, themaximum pressure may increase by a predetermined amount, by apredetermined amount up to a limit, by a function of the current maximumpressure, by a function of the current minimum pressure, and/or by afunction of the number and/or intensity of previous maximum and/orminimum pressure changes. In the illustrated example, the new maximumpressure could be used in a subsequent therapy session.

Similarly, in some configurations, if the maximum pressure deliverableis determined to be too high, the AutoPAP device may automaticallydecrease the maximum pressure. With reference to FIG. 6, a pair ofpressure versus time graphs depicting a method for adjusting the maximumpressure for an AutoPAP device is shown. On the left graph, a therapysession in which AutoPAP is used is shown. As can be observed, thesession begins at the minimum pressure and may increase to the pressureupon detecting apneas, hypopneas, or other SDBEs. The pressure mayincrease to the maximum pressure. After or over the course of amonitoring period (which may be a number of hours, a portion of atherapy session, an entire therapy session, multiple therapy sessions,or some other period of time), the amount of time T_(max) _(_) _(total)over which the device delivers the maximum deliverable pressure may becalculated or monitored. If the T_(max) _(_) _(total) is determined tobe less than or equal to a threshold percentage T % of the monitoringperiod, the device may decrease the maximum deliverable pressure. Themaximum pressure may be adjusted, for example, immediately after thedetermination, a period of time after the determination, or during asubsequent therapy session. In the illustrated example, the T_(max) _(_)_(total) (here, T₁+T₂) was found to be 4% of the monitoring period, theT % was predetermined to be 5% of the monitoring period, and themonitoring period was predetermined to be an entire therapy session. TheT_(max) _(_) _(total) was determined to be less than the T %, and so themaximum pressure 18 cm H₂O was decreased to 17 cm H₂O. In someconfigurations, the maximum pressure can decrease by a predeterminedamount, by a predetermined amount up to a limit, by a function of thecurrent maximum pressure, by a function of the current minimum pressure,and/or by a function of the number and/or intensity of previous maximumand/or minimum pressure changes. In the illustrated example, the newmaximum pressure could be used in a subsequent therapy session.

In some configurations, if the minimum pressure deliverable isdetermined to be too low, the AutoPAP device may automatically increasethe minimum pressure. With reference to FIG. 7, a pair of pressureversus time graphs depicting a method for adjusting the minimum pressurefor an AutoPAP device is shown. On the left graph, a therapy session inwhich AutoPAP is used is shown. As can be observed, the session beginsat the minimum pressure (but may begin at some other pressure) and thepressure delivered gradually increases and decreases as the patientexperiences apneas, hypopneas, or other SDBEs or the absence of SDBEs,or other conditions warranting a pressure adjustment. If the devicedetermines that a significant number of pressure-increasing SDBEs orother conditions warranting a pressure increase have occurred at or nearthe minimum pressure, the minimum pressure may be determined to be toolow. For example, the device may define an event count E_(c)representing a number of pressure increases occurring at or near (e.g.,within 1 to 3 cm H2O) the minimum pressure, an event count thresholdE_(c) _(_) _(t) and a predetermined time Tp. If the event count E_(c)over a defined time T_(p) is greater than an event count threshold E_(c)_(_) _(t), the device may increase the minimum pressure. In theillustrated example, the T_(p) was defined to be 30 minutes, the E_(c)was found to be 6 (see T1-T6 on left graph), and the E_(c) _(_) _(t) wasdefined to be 5. The E_(c) for the time T_(p) was determined to begreater than the E_(c) _(_) _(t), so the minimum pressure was raisedfrom 4 cm H₂O to 5 cm H₂O. Similarly, the minimum pressure may beadjusted, for example, after the determination, a period of time afterthe determination, or during a subsequent therapy session. In someconfigurations, the minimum pressure can increase by a predeterminedamount, by a predetermined amount up to a limit, by a function of thecurrent maximum pressure, by a function of the current minimum pressure,and/or by a function of the number and/or intensity of previous maximumand/or minimum pressure changes. In the illustrated configuration, thenew minimum pressure may be used in a subsequent therapy session.

FIG. 11 illustrates a flow chart of an example method 200 for adjustinga pressure range for respiratory therapy using an AutoPAP device. Themethod can be implemented by the devices described herein or by anyother suitable AutoPAP device configured to deliver automaticallyadjusting pressure during respiratory therapy. The method 200 can beused to adjust minimum and/or maximum pressures available to the AutoPAPdevice when providing respiratory therapy. In some embodiments, themethod 200 can be implemented by one or more software and/or hardwarecomponents on the AutoPAP device. For ease of description, then, themethod 200 will be described as being performed by an AutoPAP device.However, any other suitable configuration of modules, devices,apparatuses, and systems comprising software and/or hardware can be usedto implement one or more steps of the method 200.

In block 205, the AutoPAP device delivers pressurized gas to a patient,the pressurized gas having a pressure within an initial pressure range.The minimum and/or maximum pressures can be, for example and withoutlimitation, set by a user, a physician, a clinician, or the pressurescan be default values of the AutoPAP device. In some embodiments, theAutoPAP device limits the potential values of the minimum and/or maximumpressures available during respiratory therapy. For example, the AutoPAPdevice can be configured to not allow a minimum pressure limit to bebelow 4 cm H₂O. As another example, the AutoPAP device can be configuredto not allow a maximum pressure limit to exceed 20 cm H₂O. Thus, if oneor more conditions of the patient (e.g., the presence or absence ofSDBEs) indicate that the minimum and/or maximum pressure available fortherapy should change, the AutoPAP device can leave one or both of thepressure limits unchanged if the change would result in a pressure limitsetting that is outside of the defined allowable limits.

In block 210, the AutoPAP device measures at least one characteristiccapable of being used to determine one or more traits of asleep-disordered breathing event (SDBE), as described elsewhere herein.The at least one characteristic may be analyzed to determine the one ormore traits of a sleep-disordered breathing event of the patient, asdescribed elsewhere herein.

In block 215, the AutoPAP device analyzes the traits of asleep-disordered breathing event of the patient to determine whether tochange the pressure range limits. As described herein, the AutoPAPdevice can use measured information from the current therapy session tomake this determination. Similarly, the AutoPAP device can use measureddata from previous therapy sessions to make this determination.Moreover, the AutoPAP device can use measured data from the currenttherapy session in combination with one or more previous therapysessions or portions of one or more previous therapy sessions to makethis determination. In some embodiments, the AutoPAP device makes thisdetermination on an event-by-event basis.

In this manner, the AutoPAP device can use the method 200 toautomatically limit the range of pressures used during respiratorytherapy. This can lead to greater efficacy in respiratory therapy,greater patient compliance, and improved results relative to otherAutoPAP devices that do not adjust the pressure range limits in themanners set forth herein.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise”, “comprising”, and thelike, are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense, that is to say, in the sense of“including, but not limited to.”

Where, in the foregoing description reference has been made to integersor components having known equivalents thereof, those integers areherein incorporated as if individually set forth.

The disclosed methods, media, apparatus and systems may also be saidbroadly to consist in the parts, elements and features referred to orindicated in the specification of the application, individually orcollectively, in any or all combinations of two or more of said parts,elements or features.

Reference to any prior art in this specification is not, and should notbe taken as, an acknowledgement or any form of suggestion that thatprior art forms part of the common general knowledge in the field ofendeavor in any country in the world.

Certain features, aspects and advantages of some configurations of thepresent disclosure have been described with reference to use by apatient or user. However, certain features, aspects and advantages ofthe use of the respiratory therapy system as described may beadvantageously practiced by other people on behalf of the patient,including medical professionals, medical device dealers, or medicaldevice providers. Certain features, aspects and advantages of themethods and apparatus of the present disclosure may be equally appliedto usage by other people.

Although the present disclosure has been described in terms of certainembodiments, other embodiments apparent to those of ordinary skill inthe art also are within the scope of this disclosure. Thus, variouschanges and modifications may be made without departing from the spiritand scope of the disclosure. For instance, various components may berepositioned as desired. Moreover, not all of the features, aspects andadvantages are necessarily required to practice the present disclosure.Accordingly, the scope of the present disclosure is intended to bedefined only by the claims that follow.

What is claimed is:
 1. A respiratory therapy system comprising: a flowgenerator adapted to provide pressurized gases to a patient, a sensoradapted to measure at least one characteristic capable of being used todetermine one or more traits of a sleep-disordered breathing event(SDBE) of the patient, and a hardware controller configured to: receivethe at least one characteristic measured by the sensor, determine theone or more traits of the SDBE of the patient by analyzing the at leastone characteristic, repeatedly adjust a pressure window comprising aminimum pressure limit and a maximum pressure limit in response to oneor more parameters measured during the course of the current therapysession and/or one or more previous therapy sessions, the one or moreparameters including at least pressure delivered or the determined oneor more traits of the SDBE; and control the flow generator to deliverpressurized gases, the pressure of the pressurized gases being at leastin part based on the determined one or more traits of the SDBE, and thepressure of the pressurized gases being greater than or equal to theminimum pressure limit and less than or equal to the maximum pressurelimit, wherein the minimum pressure limit is less than the maximumpressure limit.
 2. The respiratory therapy system of claim 1, whereinthe characteristics capable of being used to determine the one or moretraits of the SDBE include one or more of the following: gas pressure,gas flow, sound, flow generator current, flow generator speed, flowgenerator motor torque, motion, tidal volume, heart rate, lung volume,EEG signal, breath composition, blood oxygen concentration, and bloodCO2 concentration.
 3. The respiratory therapy system of claim 1, whereinthe traits of the SDBE include one or more of the following: presence ofthe SDBE, absence of the SDBE, type of the SDBE, severity of the SDBE,length of the SDBE, and latency of the SDBE.
 4. The respiratory therapysystem of claim 1, wherein the controller may make a decision tomaintain or adjust the minimum pressure limit or the maximum pressurelimit on an event-by-event basis.
 5. The respiratory therapy system ofclaim 1, wherein the therapy sessions comprise only the current therapysession.
 6. The respiratory therapy system of claim 1, wherein thetherapy sessions comprise only one or more previous therapy sessions. 7.The respiratory therapy system of claim 1, wherein the therapy sessionscomprise both the current therapy session and one or more previoustherapy sessions.
 8. The respiratory therapy system of claim 1, whereinthe pressure window is adjusted in response to the pressure deliveredduring the course of the current therapy session and/or one or moreprevious therapy sessions.
 9. The respiratory therapy system of claim 8,wherein the minimum pressure limit or the maximum pressure limit isadjusted in response to the pressure delivered during one or moreprevious therapy sessions.
 10. The respiratory therapy system of claim9, wherein the delivered pressure at which the patient spent apercentage of time at or below over the course of one or more previoustherapy sessions is recorded, and the minimum pressure limit or themaximum pressure limit is adjusted to a function of the recordedpressure.
 11. The respiratory system of claim 9, wherein if the patientspends a time at the maximum pressure limit that is greater than orequal to a threshold percentage of time at the maximum pressure limitover the course of one or more previous therapy sessions, the maximumpressure limit is increased.
 12. The respiratory system of claim 9,wherein if the patient spends a time at the maximum pressure limit thatis less than or equal to a threshold percentage of time at the maximumpressure limit over the course of one or more previous therapy sessions,the maximum pressure limit is decreased.
 13. The respiratory system ofclaim 8, wherein if the patient experiences a number of deliveredpressure increases greater than a predetermined number over apredetermined period of time at or near the minimum pressure limit, theminimum pressure limit is increased.
 14. The respiratory system of claim1, wherein the respiratory system comprises an automatic positive airwaypressure therapy system.
 15. The respiratory therapy system of claim 1,wherein the minimum pressure limit or the maximum pressure limit isadjusted during a therapy session.
 16. The respiratory therapy system ofclaim 15, wherein both the minimum pressure limit and the maximumpressure limit are adjusted during the therapy session.